Diffusion transfer product having heat activatable processing system and an opacity providing layer

ABSTRACT

PHOTOGRAPHIC PRODUCTS FOR PROVIDING DIFFUSION TRANSFER IMAGE PATTERNS AND HAVING THE CAPABILITY OF BEING DEVELOPED BY HEAT. ESSENTIAL ELEMENTS OF THE PREFERRED PRODUCTS OF THE PRESENT INVENTION ARE A HEAT ACTIVATABLE PROCESSING SYSTEM INTEGRATED WITH A PELLUCID, DIFFUSION TRANSFER IMAGE PATTERN RECEIVING LAYER, A LAYER COMPRISING AN OPACIFIICATION SYSTEM WHICH CAN PROVIDE A REFLECTIVE BACKGROUND FOR VIEWING THE DIFFUSION TRANSFER IMAGE PATTERN AND AT THE SAME TIME EFFECTIVELY MASK A DEVELOPED IMAGE PATTERN IN AN UNDERLYING LAYER COMPRISING A PHOTOSENSITIVE SYSTEM.

Sept. 26, 1972 L. c. FARNEY ETAL 3,594,204

DIFFUSION TRANSFER PRODUCT HAVING HEAT ACTIVATABLE PROCESSING SYSTEM AND AN OPACITY PROVIDING LAYER Filed D60. 28, 1970 x l I I r |3- ,jLsmvER-REcEPTwE STRATUM SUBJ ECT MATTER TRANSLUCENT LAYER LIGHT-SENSITIVE LAYER SU PPORT INVENTORS LEONARE 5.1 FARNEY BY CAROLE L. GRONCKI @fcewvz cvncl United States Patent 015cc 3,694,204 Patented Sept. 26, 1972 3,694,204 DIFFUSION TRANSFER PRODUCT HAVING HEAT ACTIVATABLE PROCESSING SYSTEM AND AN OPACITY PROVIDING LAYER Leonard C. Farney, Melrose, and Carole L. Groncki, Lynnfield, Mass., assignors to Polaroid Corporation, Cambridge, Mass.

Filed Dec. 28, 1970, Ser. No. 101,630 Int. Cl. G03c 5/54 U.S. Cl. 96-29 R 25 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Part 1.The field of the invention This invention relates to photography. More precisely, the invention disclosed herein relates to photographic products useful for producing diffusion transfer image patterns.

Part 2.-Description of the prior art Photographic products for producing diffusion transfer image patterns which can be viewed without separation are also known to the art. U.S. Patent 2,861,885 issued on Nov. 25, 1958 to Edwin H. Land discloses and claims photographic products having a silver halide system which when fully developed has a low maximum density; while forming a silver transfer pattern which has a very high covering power so that the composite print may be viewed as a positive reflection print without separation.

Recently other photographic products useful for providing diffusion transfer image patterns which can be viewed without separation have been presented to the art. This particular class of products is especially useful in the preparation of photocopies of printed matter and they are described in detail in commonly assigned U.S. patent application Ser. No. 519,884 now abandoned filed as continuation-in-part of application Ser. No. 368,322 filed May 19, 1964 now U.S. Patent 3,372,104 after May 19, 1964 by Edwin H. Land and in commonly assigned U.S. patent application Ser. No. 519,995 now abandoned filed as continuation-in-part of application Ser. No. 368,321 now abandoned filed May 19, 1964 by Edwin H. Land and Leonard C. Farney.

As disclosed in these applications, a photographic product including a layer containing an opacifying system may be exposed to a light source and then processed to form a negative image and a positive transfer image in a layer situated above the layer containing the opacifying system. The opacifying system is capable of effectively masking the negative image but does not prevent photoexposure of the light-sensitive material in the photographic product. Accordingly, the product provides a composite print which contains both a negative and a positive image pattern and the positive pattern is viewable by reflection as a positive reproduction of the original subject matter.

In application Ser. No. 519,995, now abandoned, the layer containing the opacifying system is situated over a layer containing a light-sensitive silver halide emulsion;

while in application Ser. No. 519,884 now abandoned the opacifying system is situated in the same layer as the light-sensitive silver halide emulsion and a second or additional layer containing an opacifying system may also be provided over the layer containing the silver halide emulsion.

Any of the aforementioned photographic products may contain an outer layer comprising a silver receptive layer, i.e., a layer containing at least one silver precipitating agent, or the silver precipitating agent may be present initially in the processing composition.

The photosensitive system of photographic products of the type mentioned above may contain a silver halide emulsion and preferably a mixed silver halide emulsion, having a relatively high film speed. Also, excellent results have been obtained employing emulsions containing a relatively small amount of silver. For example, application Ser. No. 519,995 now abandoned discloses that the silver halide in the photographic products described and claimed therein may be present in an amount suflicient to provide a silver coverage on the order of from about 0.02 to about 0.1 g. per sq. ft. surface area. Moreover, application Ser. No. 519,884 now abandoned discloses that the silver halide present in the single layer film units, i.e., the film units containing no second or additional layer of opacity-providing material, may be present in an amount suflicient to provide a silver coverage with as little as 0.0018 g. per sq. ft., while in the two-layer film units, i.e., those containing a second layer of opacityproviding material, the silver halide is previously present in an amount suflicient to provide a silver coverage of at least 0.01 g. per sq. ft.

Development of exposed photographic products of the above described type usually involves a processing composition comprising an aqueous alkaline solution of a silver halide developing agent and a silver halide solvent. These ingredients may be present initially in the aqueous medium for the processing composition. Alternatively, any or all of the ingredients may be present initially in the film unit, e.g., by encapsulation, as discrete coatings, etc., in which case development is initiated by contacting the film unit with an aqueous medium to form the processing composition. Also, as described in commonly assigned copending application of Edwin H. Land, Ser. No. 519,885 filed J an. 11, 1966 now U.S. Patent 3,362,823, development of the exposed film unit may be effected by impregnation with a non-alkaline processing composition and the alkalinity required to initiate development may be generated in situ electrolytically at some time subsequent to impregnation. The processing composition may also contain other reagents such as a viscosity-increasing, filmforming material, for example, sodium carboxymethyl cellulose, hydroxyethyl cellulose, etc., preservatives, antifoggants, and the like.

In some instances, the processing composition may also contain silver precipitating nuclei. Such processing compositions are disclosed, for example, in U.S. Pat. No. 2,662,- 822 issued to Edwin H. Land. It is also contemplated that the silver precipitating nuclei may be generated in situ electrolytically according to the procedures described and claimed in the commonly assigned copending application of Ronald F. Cieciuch, Ser. No. 519,886 filed Jan. 11, 1966 now U.S. Patent 3,549,363 or a soluble fogging agent may be contained in the processing composition according to the procedures described and claimed in the commonly assigned copending application of Leonard C. Farney, Ser. No. 519,967 now abandoned filed Jan. 11,

Additional patent applications relating to photographic products of the type to which the present invention pertains include commonly assigned applications Ser. Nos.

519,955 now abandoned and 526,673 both filed by Leonard C. Farney on Jan. 11, 1966. Application Ser. No. 519,955 relates to photographic products wherein a siliceous materialpreferably a finely granulated colloidal silica is incorporated in layer containing the opacifying system. The presence of the siliceous material enhances the covering power of the opacifying system and increases the effectiveness of the silver in the transfer process by which the positive image is obtained. Application Ser. No. 526,673 relates to photographic products which include an effective amount of a photographically innocuous humectant which materially lowers the processing time and/ or the amount of processing composition necessary to form a silver image by diffusion transfer.

Also US. patent application Ser. No. 519,885 filed Jan. 11, 1966 by Edwin H. Land relates to modified photographic products of the aforedescribed type. Specifically, the application discloses and claims photographic product so structured that the resulting composite print may be View through a transparent support as a positive reflective print or from the opposite side, i.e., from the light sensitive layer side, as a negative image.

The present invention is directed to novel photographic products which present certain improvements over the photographic products heretofore known to the art such as those described and claimed in the above mentioned patent applications.

SUMMARY OF THE INVENTION *In accordance with the practice of the present invention, there is presented to the art, novel photographic products which have the capability of being developed by heat. In accordance with the preferred embodiment of the present invention, novel photographic products are presented which can provide diffusion transfer image patterns viewable by reflection without separation and which have the additional capability wherein such image patterns can be developed by heat.

The novel photographic products of the present invention as well as the essential elements thereof will be more fully understood by reference to the following description taken in connection with the accompanying drawing wherein:

The figure is a partially schematic, partially enlarged fragmentary sectional view illustrating a preferred film unit of this invention and the photoexposure thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figure, a preferred film. unit 1 of this invention comprises essentially, in order, a support 10, which is preferably opaque, having thereon a lightsensitive layer 11, e.g., a light-sensitive silver halide emulsion and a pellucid, e.g., transparent or translucent layer 12 preferably comprising an opacifying material which is at least permeable to but substantially insoluble in a moisture activatable processing system to be described with more particularity hereinafter. r'Ihe film unit 1 also includes an image receiving layer 13 which is preferably substantially transparent.

Light-sensitive layer 11 preferably comprises a gelatino silver halide emulsion which upon development will form a negative silver image of relatively low density or covering power. Accordingly, the layer preferably contains a mixed halide emulsion, e.g., a silver iodobromide emulsion. Additionally, light sensitive layer 11 usually has a pH between about 6.5 and about 8.5 and comprises a specific heat activatable system including as essential components thereof, a silver halide developing agent and a silver halide transfer agent. The function of this heat activatable system as well as the agents thereof and the manner in which the agents are integrated with photographic products of the present invention will be more apparent from the following detailed description. In the especially preferred embodiment of the present invention, layer 11 also in- 4 cludes an opacifying system, e.g., an opacifying material which will be described in more detail hereinafter in the description of layer 12.

In the preferred embodiment of the present invention, pellucid layer 12 comprises an opacifying system which may be an opacifying material such as finely divided titanium dioxide, calcium carbonate, magnesium oxide, bar ium sulfate, etc., or a mixture of such materials, dispersed in a suitable permeable colloidal carrier or matrix such as gelatin. The opacifying material is present in an amount sufficient to effectively mask the negative silver image formed after development in light-sensitive layer 11 but the amount of opacifying material is insuificient to preclude photoexposure of the light-sensitive layer from a light source on the same side of the support as the two layers =(e.g., in the manner shown in the figure). Accordingly, the opacifying material further serves to provide a background, preferably a white background, for viewing the composite print, without separation, by reflected light as a positive silver image.

As used herein and in the appended claims, the term effectively masking denotes the ability of the opacifying material to sufficiently mask or obscure the negative image so that the composite print is viewable as a positive image.

It is to be understood that in some of the products embraced within the scope of the present invention, layer 12 containing an opacifying system need not be present and in some products, an opacifying system need not be present. For example, as mentioned, the opacifying system can be included in light sensitive layer 11. Also a heat activatable developer system of the type described in more detail hereinafter can be integrated in photographic structures such as those described in the aforementioned US. Patent 2,861,885 in lieu of the processing compositions shown therein to provide photographic products for producing diffusion transfer image patterns developable by heat and which can be viewed without separation.

Pellucid, image-receiving layer 13 has a pH between about 9.5 to about 10.5 and comprises one of the known vigorous silver precipitating environments containing silver-precipitating nuclei, e.g., at least one silver-precipitating agent dispersed in a microscopically continuous vehicle. A dispersion of such nuclei in a colloidal material such as colloidal silica or gelatin can provide suitable pellucid image-receiving layers for products of the present invention. Additionally, pellucid, image-receiving layer 13 preferably comprises an ingredient which can selectively prevent diffusion thereto or deposition therein of any substantial amount of visible silver from the exposed and developed portions of light sensitive layer 11.

Referring again to the figure, the subject matter 14, e.g., a document having areas which are opaque, e.g., printing and areas which will transmit visible light, is shown positioned between a suitable light source 15 and silver receptive layer 13 of the photographic product. It will be appreciated that the photographic product is confined in a camera or other suitable device so that lightsensitive layer 11 is photoexposed for the requisite time only to light transmitted through or reflected from subject matter 14, thereby to form a developable image in terms of the light-transmittant areas of the subject matter.

After exposure, photographic products of the present invention can be developed by heat. This development is achieved by integrating a heat activatable system including a silver halide developing agent and a silver halide transfer agent with the elements of the photographic products. The integration is such that in the presence of heat, the silver halide developing agent can reduce exposed silver halide while at least part of the imagewise distribution of soluble silver complex formed from unreduced silver can be transferred to layer 13 by the silver halide transfer agent.

The manners in which the heat activatable system is integrated with the essential elements of the photographic products of the present invention can vary. For example, the silver halide developing agent and/or the silver halide transfer agent can be included separately or together in any of the layers mentioned before. However, in the preferred embodiment of the present invention, at least the developing agent is included in light sensitive layer 11 and in the especially preferred embodiment, both the developing agent and the transfer agent are included in light sensitive layer 11.

Silver halide developing agents are known to the art and include among others, hydroquinone and derivatives of hydroquinones such as 4'-methylphenyl hydroquinone etc., catechol and derivatives of catechol, such as 4-phenyl catechol etc., derivatives of naphthol, such as 4-methoxyl-naphthol, derivatives of phenol such as methyl paraaminophenol etc., the 3-pyrazolidones, such as l-phenyl-3- pyrozolidone. The especially preferred silver halide developing agents in the practice of the present invention are metol, phenidone, pyrocatechol, methyl hydroquinone and toluyl hydroquinone.

The compounds which function as silver halide transfer agents of the present invention are succinimide, the alkali metal sulfites or combinations thereof. The transfer agents of the present invention are surprisingly compatable with silver halide developing agents and they can be included in silver halide emulsion layers in combination with such developing agents. As those skilled in the art know, silver halide transfer agents, e.g., silver halide solvents or silver halide complexing agents heretofore employed in the diffusion transfer art are not conveniently included in silver halide emulsion layers containing silver halide developing agents. For example, the inclusion of transfer agents such as thiocyanates, thioureas, thiosulfates and mercapto containing compounds in emulsion layers containing developing agents can desensitize, fog, spot or otherwise adversely affect the quality of the diffusion transfer image pattern obtained on exposure and development of such emulsions. Moreover, it should be mentioned that succinirnide and alkali metal sulfites have not been regarded in the art as effective transfer agents in silver halide diffusion transfer systems.

The particular amounts of developing agent and transfer agent employed and the ratio of one to the other can vary. For example, the silver halide developing agent can be employed in amounts between about 0.1 and about .1 g./ft. and the silver halide transfer agent can be employed in amounts betwen about 0.04 to about 0.4 g./ft.

In addition to the above mentioned essential ingredients of the moisture activatable system, auxiliary materials may be included in the photographic products of the present invention to provide predesired properties such as stability, image density, processing time and/or related considerations. Such auxiliary ingredients include water and/ or alkali precursors, e.g., materials which in the presence of moisture produce, liberate or otherwise provide water or alkali. Water precursors are known to the art and representative species include, among others, sugars, fl-nitroethanol, and hydrated salts, e.g., acetates, silicates and phosphates. Alkali precursors are also well known to the art and a particularly preferred class of such precursors include compounds which in the presence of moisture release ammonia or amines. Representative species of alkali precursors include urea, N-methylurea, formamide, sulfamide, glutarimide and the like.

As mentioned, in the preferred embodiment of the present invention, the silver halide developing agent as well as the silver halide transfer agent are included in light sensitive layer 11. Also in the preferred embodiment, layer 11 contains an opacifying material which can be the same material providing the opacifying system of translucent layer 12. An especially suitable opacifying material for inclusion in layer 11 is titanium dioxide with the amount involved being sufiicient to provide between about 800 to about 2000 mgrns./ft. of titanium dioxide in layer 11.

After exposure, the photographic product of FIG. 1 is heated to activate the aforementioned processing systern. Upon heating 0 fthe exposed product the processing system reduces exposed silver halide in layer 11 while substantially simultaneously forming an imagewise distribution of soluble silver complex from unreduced silver. At least part of the complex is transferred through pellucid layer 12 to image-receiving layer 13 where it is reduced to image silver to provide a positive silver transfer image pattern.

The composite print comprising the positive silver image superimposed upon the negative image therebeneath may be viewed as a positive reflection print having an acceptable low D due to the opacity of layer 12 effectively masking or substantially obscuring the negative image therebeneath.

As previously mentioned, transparent image-receiving layer 13 preferably comprises an ingredient which can selectively prevent diffusion thereto or deposition therein of any substantial amounts of visible silver from the exposed and developed portions of light sensitive layer 11. In the absence of such an ingredient, the soluble complex providing the positive image pattern is transferred to layer 13 initially but apparently silver from exposed portions of layer 11 can also be transferred to or deposited in layer 13.

This transfer of silver from exposed portions of layer 11 can ultimately prevent effective discrimination between the positive and negative patterns. The effect of this unwanted visible silver in layer 13 is not especially apparent when succinimide is employed as a transfer agent but is especially apparent when the alkali metal sulfites are so employed. Accordingly, in the especially preferred embodiments of the present invention, layer 13 comprises an ingredient which can effectively prevent this unwanted silver from being diffused thereto or otherwise deposited therein.

Ingredients which can function in the above described manner and which are preferred in the practice of the present invention are compounds conforming to the following tautomeric formulae:

CSH It C 0 1 1 1&1

FORMULA l NN Rat 5 FORMULA 2 wherein R can be hydrogen, hydroxyl, amino, lower alkyl of from 1-4 carbon atoms, lower alkoxy of from 1-4 carbon atoms, an aryl radical, e.g., phenyl, tolyl or a heterocyclic radical, e.g., pyridyl, provided that only one R of Formula 1 can be hydrogen and the other is as defined; R is -S, O-- or R can be hydrogen, halogen, lower alkyl, aryl or lower alkoxy group.

Representative compounds of Formula 1 include the following:

C I C Representative compounds of Formula 2 include the following:

halide in layer 11 should be present in an amount sufficient to provide a silver coverage on the order of from about 0.02 to about 0.1 gm. per sq. ft. of surface area, although good results have been obtained with as little as 0.006 gm. per sq. ft. The ratio of colloidal binder, e.g., gelatin, to silver is preferably from about 5:1 to about 10:1.

It has also been found that the presence in layer 11 of a photographically innocuous humectant such as amethyl glucoside materially lowers the processing time and/ or the amount of processing composition necessary. This is apparently due to the ability of the humectant to retain water in the emulsion matrix which in turn minimizes shrinkage or, stated another way, minimizes the swelling needed for processing, thus lowering the induction time and/ or the time required for the soluble silver complex to transfer to the layer where it is reduced to .image silver. This concept of providing a humectant in the emulsion layer is described with more particularity, and claimed in the aforementioned copending application of Leonard C. Farney, Ser. No. 526,673.

As was mentioned previously, in the preferred embodiment the opacifying material in pellucid layer 12 is present in an amount sufiicient to mask effectively, the negative image formed in layer 11 and to provide the background for viewing the composite print as a positive reflection print. Also, thearnount of opacifying material is insufficient to preclude photoexposure, and most preferably, insufficient to affect adversely, i.e., to lower the film speed of the product, at least to any appreciable extent. For optimum results, ranges on the order of at least 0.1, e.g., from about 0.1 to about 2.0 gm. of opacifying material per sq. ft. of surface area have been found to be desirable with from about 0.8 to about 1.5 gm. per sq. ft. providing particularly satisfactory results in terms of density, contrast and stability.

The ratio of opacifying material per sq. ft. in layer 12 to silver per sq. ft. in layer 11 is preferably on the order of from about 30:1 to about 50:1.

With amounts of opacifying material on the order to that described above, it has been found that the film speed is approximately the same as would be obtained if no opacifying material were present. In other words, with substantially same quantum or level or exposure, one

-may obtain an image having a density comparable to that obtainable from a similar photographic product having no opacifying material.

The present invention thus makes it possible for one to obtain positive silver transfer images of good density Urea-2.4 gms.

Hydroquinone.4 gms. Succinimide-2.4 gms.

Ag IBr emulsion (6.5% Ag)5.8 ml's.

Coat the above coating mixture on paper, preferably on the coated surface of a paper coated with cellulose trlacetate to render the surface water impermeable, at a rate of 4.8 cc./ft. to provide an emulsion coating containing 0.04 gm. silver halide/ft.

Prepare a silver diffusion transfer receptive layer by mixing the following ingredients and coating the mixture on the emulsion layer at a rate of 1.04 cc./ft.

9 Ludox (30% soln.)50 mls. Water-50 mls. I AgNO (0.5 N)-1 ml. Sodium sulfide (1 N)-0.5 ml. Wetting agent (25% triton X100)-.5 cc. Enough Na CO to obtain a pH of 10 As mentioned, in the practice of the present invention, the pH of the diffusion transfer layer (layer 13) is considered critical and should be between about 9.5 to about 10.5.

After the receptive layer is dry, expose to an image pattern under 9000 meters candle seconds and thereafter place the so exposed product on a heated platen (300 F.) for 10-15 seconds to obtain a positive image pattern with a D of .90 and a D of .32.

Example 2.-Prepare a titanium dioxide slurry by mixing together the following ingredients:

TiO (pigment grade) 12 gms. gelatin soln.750 mls. Methyl glucoside37.5 gms. Wet-ting agent (Daxad 30)3 mls. Water-900 mls.

Prepare a coating mixture by taking 54 grams of the above Ti0 slurry and mixing the slurry with the following ingredients:

Urea-4.8 gms.

Hydroquinone0.8 gm.

Sodium sulfite0.8 gm. Ag IBr emulsion (6.5% Ag)5.8 mls.

Coat the above mixture on paper, preferably on the coated surface of a paper coated with cellulose triacetate to render the surface water impermeable at a rate of 4.8 cc./ft. to provide an emulsion coating containing 0.04 gms. silver halide/ftF.

After the emulsion layer is dry, coat on the above prepared titanium dioxide slurry at 4.8 cc./min.

Prepare a silver diffusion transfer receptive layer by mixing the following ingredients and coating the mixture on the titanium dioxide containing layer at a rate of 2.08 cc./min.

Ludox (30% soln.)50 mls.

Water50 mls.

AgNO (0.5 N)l ml.

Sodium sulfide (l N).5 ml. succinimide-4.0 gms. 2-thiouracil-0.025 gm. Wetting agent (25 triton X-l00)--.5 cc.- Enough Na CO to obtain a pH of 10.

After the receptive layer is dry, expose to an image pattern under 9000meter candle seconds and thereafter place the so exposed product on a heated platen (300 F.) for 10-15 sec. to obtain a positive image pattern.

Example 3.Repeat the procedure of Example 2 but substitute 1 ml. 0.5 N Ni(NO for the AgNO in the diffusion transfer layer of Example 2.

Example 4.-Repeat the procedure of Example 2 but do not coat the titanium dioxide slurry on the silver halide emulsion layer and instead coat the diffusion transfer layer mixture directly on the emulsion layer to provide a product having the opacifying system distributed in the emulsion layer. After processing as in Example 2, a positive image with a Dmax, of .90 is obtained.

Example 5.Repeat the procedure of Example 1 but coat the slurry of Example 2 on the emulsion layer of Example 1 to provide a product wherein the opacifying system is interposed between the emulsion layer and receptive layer.

After the receptive layer is dry, expose to an image pattern under 9000 meters candle seconds and thereafter place the so exposed product on a heated platen (300 F.) for l0-15 seconds to obtain a positive image pattern.

Example 6.Repeat the procedure of Example 2 but leave out the 4.8 gms. of urea in the emulsion mixture of Example 2 and leave out the 4 gms. of succinimide in the mixture for preparing the receiving layer of Example 2.

Example 7.Repeat the procedure of Example 2 but add 1.2 gms. succinimide to the emulsion mixture and leave out the 8 gms. of succinimide in the mixture for preparing the receptive layer.

As will be apparent from the foregoing description and illustrative examples of the preferred embodiment, the present invention provides novel film products comrising a layer of opacifying material superposed on a lightsensitive layer, which film product is exposed through the pellucid layer and then processed by heat, to form a composite print containing a visible transfer image which may be viewed by reflection as a positive image.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A diffusion transfer photographic product for forming a composite print wherein a positive image is formed in an image-receiving layer arranged in combination with a light sensitive layer containing a negative image so that said positive image is viewable by reflection without separation; said product comprising as essential elements thereof a light sensitive silver halide emulsion layer, a receiving layer which can receive a diffusion transfer positive image pattern and wherein the pH of said receiving layer is between about 9.5 to about 10.5 and a heat activatable developing system comprising a silver halide developing agent and a silver halide transfer agent chosen from the group consisting of alkali metal sulfites, succinimide, or mixtures thereof integrated with said elements so that the product can be developed by heat.

2. A photographic product of claim 1 further including an opacifying system.

3. A photographic product of claim 1 wherein said light sensitive layer comprises an opacifying system.

4. A photographic product of claim 1 including a layer comprising an opacifying system interposed between said receptive layer and said light sensitive layer.

5. A photographic product for forming a composite print wherein a positive image is formed over a negative image and said positive image is viewable by reflection without separation, said product comprising as essential elements thereof a support substantially opaque to visible light, a first layer on the support containing a light sensitive silver halide emulsion, a second layer on said first layer containing an opacifying system which can efiec tively mask a developed negative image pattern in the first layer and a silver receptive layer which can receive a positive diffusion transfer image pattern from the light sensitive layer and wherein the pH of said receptive layer is between about 9.5 to about 10.5 and a heat activatable developing system comprising a silver halide developing agent and silver halide transfer agent chosen from the group consisting of alkali metal sulfites, succinimide or mixtures thereof integrated with said elements so that the product can be developed by heat.

6. A product of claim 5 wherein the light sensitive layer contains the silver halide developing agent or the silver halide transfer agent.

7. A product of claim 5 wherein the light sensitive layer contains an opacifying system.

8. A product of claim 5 wherein said transfer agent comprises sodium sulfite.

9. A product of claim 5 wherein said transfer agent comprises succinimide.

10. A product of claim wherein the light sensitive layer contains the silver halide developing agent and the silver halide transfer agent.

11. A product of claim 8 wherein said transfer agent comprises sodium sulfite.

12. A product of claim 5 wherein said opacifying system comprises a white pigment as an opacifying material.

13. A product of claim 5 wherein said opacifying system comprises titanium dioxide as an opacifying material.

14. A product of claim 5 wherein said silver-receptive stratum comprises at least one silver-precipitating agent dispersed in a colloidal carrier.

15. A product of claim 5 wherein the silver halide in said first layer is present in an amount sufiicient to provide a silver coverage of from about 0.02 to about 0.l gm. per sq. ft. of surface area.

16. A product of claim 5 wherein said emulsion comprises a mixed silver halide emulsion and said material is present in an amount insuflicient to lower, at least to any appreciable extent, the film speed of said product.

17. A product of claim 5 wherein said opacifying system comprises a white pigment material in an amount suflicient to provide from about 0.1 to about 2.0 gm. of opacifying material per sq. ft. of surface area.

18. A product of claim 5 wherein said opacifying system comprises a white pigment material in an amount suflicient to provide a ratio of opacifying material per square foot in said second layer to silver per square foot in said first layer of from about 30:1 to about 50:1.

19. A product of claim 5 wherein the silver receptive layer comprises a compound conforming to the following tautomeric formulae:

radical provided that if one R of Formula 1 is hydrogen, the other is as defined above, R is and R can be hydrogen, halogen, alkyl, aryl or alkoxy.

20. A product of claim 5 wherein the receptive layer comprises a compound selected from the group consisting of Z-thiouracin, 2-thiobarbituric acid or mixtures of these.

12 21. A product of claims wherein the light sensitive layer contains the silver halide developing agent and a silver halide transfer agent chosen from the group consisting of succinimide, sodium sulfite or mixtures thereof and the silver receptive layer comprises a compound conforming to the following tautomeric formulae:

li (IF811 I I R=*-C\ N R C\ /NH F "i wherein each R can be hydrogen, hydroxyl, amino, lower alkyl, lower alkoxy, an aryl radical or a heterocyclic radical provided that if one R of Formula 1 is hydrogen, the other is as defined above, R is and R can be hydrogen, halogen, alkyl, aryl or alkoxy.

22. A product of claim 21 wherein said transfer agent comprises sodium sulfite.

23. A product of claim 5 wherein the silver receptive layer comprises a compound chosen from the group consisting of 2-thiouracil, 2-thiobarbituric acid and mixtures of these and the light sensitive layer contains hydroquinone and sodium sulfite.

24. A photographic process comprising the steps of exposing a photographic product of claim 1 to a source of activating radiation and contacting the exposed product with heat;

25. A photographic process of claim 24 wherein a product of claim 5 is exposed to a source of activating radiation and said product is contacted with heat after exposure.

References Cited UNITED STATES PATENTS 3,578,450 5/1971 Miller 96-76 3,152,904 10/1964 Sorensen et a1. 96-76 2,759,819 8/1956 Levy et al. 96114.1 3,080,254 3/1963 Grant 9648 HD FOREIGN PATENTS 1,123,203 9/1960 Germany 96-48 PD 1 NORMAN G. TORCHIN, Primary Examiner 'J. L. GOODROW,'Assistant Examiner U.S. Cl. X.R. 96-66 T 

